http://www.pcgamer.com/latest-amd-gpu-driver-is-optimized-for-warhammer-ii-and-forza-motorsport-7/

For the second time in less than a week, AMD has another Crimson ReLive driver package available. The new 17.9.3 driver release is optimized for a couple of games that are coming soon—Total War: Warhammer II due out tomorrow, and Forza Motorsport 7.

The release notes indicate that multi-GPU support for Warhammer II is included in the new drivers, along with a Radeon Chill profile. There is no mention of multi-GPU support specific to Forza Motorsport 7.